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JACK 5.4 Application Interface | |||||||||
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java.lang.Objectaos.jack.jak.util.Watchable
aos.jack.jak.cursor.Cursor
The Cursor class is the underlying implementation for returning values from queries of any type.
Field Summary | |
static BeliefState |
FALSE
Represents a false value. |
static Cursor |
falseCursor
Utility instance for queries that return false always. |
static BeliefState |
TRUE
Represents a true value. |
static Cursor |
trueCursor
Utility instance for queries that return true always. |
static BeliefState |
UNKNOWN
Represents an unknown value. |
Constructor Summary | |
Cursor()
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Method Summary | |
void |
finished()
This informs the cursor that it is not going to be used again. |
boolean |
isTriggered()
Used by JACK to determine if the cursor provides triggering. |
Cursor |
negate()
This is called to negate the value of the cursor. |
abstract boolean |
next()
This method is called to provide a next binding by this cursor. |
void |
register(java.util.Observer o)
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Cursor |
reset(aos.jack.jak.core.Generator g,
int index)
Resets the cursor. |
void |
undo()
Undo tells the cursor to backtrack anything it has done. |
boolean |
unRegister(java.util.Observer o)
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Methods inherited from class aos.jack.jak.util.Watchable |
addObserver, countObservers, deleteObserver, deleteObservers, hasChanged, notifyObservers, notifyObservers |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
public static final BeliefState TRUE
public static final BeliefState FALSE
public static final BeliefState UNKNOWN
public static final Cursor trueCursor
public static final Cursor falseCursor
Constructor Detail |
public Cursor()
Method Detail |
public abstract boolean next()
db.query($x) && isWhatIWant($x) && db1.query($x, $y)If the isWhatIWant() cursor simply tests its input and returns true for appropriate values then this expression would not work as expected and may go into an infinite loop.
db(1) db(2) db(3) db1(3,3)and isWhatIWant() returned true on odd numbers. Then the correct behaviour would be one result with $x=3 $y=3. However if isWhatIWant.next() always returns true on odd numbers then: $x is bound to 1,
public Cursor reset(aos.jack.jak.core.Generator g, int index)
g
- The generator that generates an equivalent cursorindex
- The index of the equivalent cursor in the generator.
public Cursor negate()
public void undo()
public void finished()
public boolean isTriggered()
public void register(java.util.Observer o)
public boolean unRegister(java.util.Observer o)
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US Government Restricted Rights
The JACK Modules and relevant Software Material have been developed entirely at private expense and are accordingly provided with RESTRICTED RIGHTS. Use, duplication, or disclosure by Government is subject to restrictions as set forth in subparagraph (c)(1)(ii) of DFARS 252.227-7013 or subparagraph (c)(1) and (2) of the Commercial Computer Software Restricted Rights and 48 CFR 52.2270-19, as applicable.